1. Field of Art
This invention relates to the improvement of a hydro-mechanical transmission on an agricultural combine. More specifically, the invention is controlling the rotation of a threshing rotor on a combine.
2. Description of Prior Art
Mechanical harvesting of grain has taken place for decades. However, efforts continue in the attempt to make harvesting operations more efficient and effective. A combine harvester generally includes a header, which cuts the crop. The header then moves the cut crop into a feeder house. The feeder house lifts the cut crop into the threshing, separation and cleaning areas of the combine. The grain is separated from the stalk by a rotor or cylinder threshing system. The grain is then separated and moved and stored in a grain tank. The chaff and trash are deposited from the rear of the combine. The grain stored in the grain tank is eventually discharged through a grain tank unload tube. An operator usually runs these various operations from a glass-enclosed cab. Typically, the cab is located above and behind the header and feederhouse. There are a variety of agricultural combine harvesters and their operations are well known in the art. For examples of such harvesters reference U.S. Pat. No. 4,846,198 which illustrates the conventional and twin rotor threshing and separating systems of a harvester as well as other major systems of the harvester. See also the New Holland Super Conventional Combines TX.TM. 66, TX.TM. 68, the New Holland TWIN ROTOR.RTM. combines TR.RTM. 89 and TR.RTM. 99 for examples of existing conventional and twin rotor harvesters. U.S. Pat. No. 4,332,262 also illustrates the primary systems of a conventional harvester. For further details regarding various agricultural harvester systems review U.S. Pat. Nos. 4,522,553, 4,800,711, 4,866,920, 4,907,402, 4,967,544 and 5,155,984. See also the New Holland corn head model 996 and the New Holland grain belt header model 994 for details regarding headers.
The previously mentioned threshing and separating system consists of several elements. These include the rotor, concave, grain pan, sieves and fans. Of critical importance is the control of the rotation of the rotors. Typically, the engine would transmit rotational energy to the rotor by a belt drive. The belt drive could be engaged by a clutch or variable sheave arrangement. However, in order to increase the amount of crop processed by the harvester, the size, weight and power consumption of the rotors are being increased to levels above the tolerances of belt driven technology. To prevent the loss of the belt (and consequently the rotation of the rotor), hydro-mechanical systems have been used to transmit the rotational energy from the engine to the rotor. Additionally, it is difficult to start rotating a heavy rotor under certain crop conditions. Besides placing an enormous amount of stress on the belt drive, there is an enormous amount of stress placed on the clutch used to engage the belt drive. The stress on the clutch can be severe resulting in early clutch failure. Additionally, there are instances where crop becomes plugged between the rotor and concave. In this situation it may be desirable to briefly reverse the rotation of the rotor to force the plug out.
The prior art illustrates these and other difficulties. U.S. Pat. No. 5,865,700 illustrates a hydro-mechanical transmission. The transmission is powered by an engine and hydrostatic motor which derives its' power from the engine. A single clutch controls the input of the engine power and input of the hydrostatic motor power by means of a control circuit. However, if input from the hydrostatic motor is not precisely synchronized the input of the hydrostatic motor could brake the engine resulting in potentially disastrous damage to the engine. U.S. Pat. No. 5,667,452 discloses a split torque transmission and U.S. Pat. No. 4,019,404 discloses a power transmission. In both designs there are limits to the ability to slowly engaging the clutch so as to prevent damage.
A hydro-mechanical transmission that would allow the rotation of the clutch and rotor to be slowly increased without damage to the clutch would be a great improvement. An invention that could resolve these issues would represent an improvement to the art.